Dynamical states of a mobile heat blanket on a thermally convecting fluid

We experimentally study the dynamical states of a freely moving, floating heat blanket that is coupled with a thermally convecting fluid. This floating boundary modifies the large-scale flow pattern in the bulk and destabilizes the coupled system, leading to spontaneous oscillations. As the moving boundary exceeds a critical size, the system makes a transition from an oscillatory state to a weakly confined state, in which the moving boundary executes only small excursions in response to random bypassing thermal plumes. To explain the observed states and transition, we provide a low-dimensional model that appears to capture the underlying mechanism of this coupled system.